[antoko]

His point seems to be that it breeds HONESTY rather than meanness, I don't think he was saying it breeds the opposite of meanness, just that meanness is a side-effect of the honesty and the honesty is the real effect.

[angersock]

Exploring that just a little further...

The meanest things are those with a grain of truth in them, a mirror for someone's imperfections.

Thus, it follows that a community which enables blatant and rough honesty will be perceived as "meaner".